Over these past few years, hybrid vehicles and electric vehicles, which are types of vehicles other than engine automobiles that are driven only by an engine, have become popular. A hybrid vehicle is driven by a drive source that uses both an engine and a motor, and an electric vehicle is driven by a motor as types of vehicles other than engine vehicles that are powered only by an engine. In this type of electrically-driven vehicle, the battery must be charged when the voltage of the battery decreases. When performing the charging with a household power supply (commercial power supply: AC 100 V), the charging is carried out by connecting an input of an external charging device, such as a charging cable, to a household socket and connecting an output of the external charging device to a charging connector of the vehicle.
When charging the battery with a household power supply, the battery of the electrically-driven vehicle may be charged, without any limitations, with the power supplied from the household socket by simply plugging in the external charging device to a household socket. Therefore, if the electrically-driven vehicle is stolen, the thief would be able to continuously drive the stolen vehicle since the battery of the stolen vehicle can be repeatedly charged by a household power supply by using the external charging device. It is believed that this is a factor that leads to theft of an electrically-driven vehicle. Thus, it is required that an anti-theft measure be provided to reduce the number of vehicle thefts.
Patent document 1 discloses an example of a charging action authentication system for the charging of a battery of an electrically-driven vehicle in order to increase the anti-theft capability of an electrically-driven vehicle. This technique uses a read-write device capable of reading information from an IC card, which is used as a vehicle key, and writing information to the IC card. When performing charging with the charging device, the authorized user removes the IC card from the vehicle and inserts it into the read-write device. If the IC card is authenticated, the battery charging of the battery is permitted.
However, even when employing the technique of limiting charging actions through the authentication establishment of an IC card, the battery can still be charged if the IC card is stolen. In such a case, this technique is ineffective. Particularly, since the owner of the IC card usually carries the IC card, the IC card may be stolen if the owner is not careful. Accordingly, the prevention of vehicle theft cannot be sufficiently ensured regardless of the employment of a system that carries out authentication when charging is performed with a household power supply.    [Patent Document 1] Japanese Laid-Open Patent Publication No. 10-262303